Alias and ID fields for questions and answers.. what do they do?

Can you point to a bit more info on what these fields allow us to do? We're trying to better reference the answer to a certain question at the start of the survey (which company do you work for dropdown) and are seeing if these fields may better help us link
to that answer when looking at survey results.

Alias and ID fields are optional and can be set manually. Until now (SP 2.3) they are not used or referenced elsewhere in the application. Data are saved to the database from where they can be used in queries or reports.